Kr Xe Mixtures Research Articles

Enhanced production of tunable VUV radiation by phase-matched frequency tripling in krypton and xenon

Nonresonant frequency tripling of intense dye laser radiation in negative dispersive Kr ( \lambda = 1203-1235 A ) is efficiently enhanced by phase matching with the positive dispersive tare gas Ar or Xe. Phase matching of Kr with Ar improved the efficiency of the conversion of 3648 A to L_{\alpha} = 1216 A by more than two orders of magnitude. At L_{\alpha}, 16 W ( 4 \cdot 10^{10} photons/pulse) could be generated with 1.5 MW pulses of a frequency doubled dye laser. The optimum conversion is limited by absorption of the VUV in the rare gas mixture and by dielectric breakdown. In mixtures of Kr and Xe, the dependence of the VUV on the density of the two gas components indicates a phase difference between their contributions to the induced third-order polarization. Measurements of the VUV output of different Kr-Xe mixtures provide a determination of the ratio of the third-order nonlinear susceptibilities χ Kr /χ Xe and of the wave vector mismatches per atom C Kr /C Xe at wavelengths \lambda = 1205-1230 A Besides frequency tripling in Kr, third-harmonic generation of blue dye laser light ( \lambda = 4208-4406 A) has been investigated in Xe phase matched with Kr. The peak power of the tunable VUV at \lambda = 1403-1469 A exceeded 30 W ( 8.7 \cdot 10^{10} photons/pulse).

Energy transfer kinetics of the VUV emissions for Kr–Xe mixtures

Spectroscopic study of KrXe mixtures shows large excitation energy transfers from krypton to xenon. When small quantitities of xenon are added to krypton, these processes can be seen through the fast disappearance of the continuous krypton emissions coupled with an increase in the atomic and molecular emissions of the minority gas. The excitation transfers are very efficient since the spectra of mixtures with only a few percent Xe are very similar in shape and intensity to those of pure xenon. Kinetic analysis of all the VUV emissions enabled a complete kinetic schema of the transfer phenomena to be drawn up. They are due to binary collisions from the molecular states, Kr*2(3Σu+), which are responsible for the second krypton continuum (k2=2.107 Torr−1 s−1) and from the atomic precursor states of molecular krypton (k1=7.106 Torr−1 s−1). Both processes have large cross sections. The two paths compete in the creation of resonant Xe(3P1) states, either through direct molecule–atom transfer or by atom–atom transfer followed by infrared cascade emissions. In the mixture, the molecular Xe2* states responsible for the 173 nm continuum have a different origin to that found in the pure gas. They are created by three-body collisions Xe*(3P1)+Xe+Kr; the reaction constant is k=40±10 Torr−2 s−1.

The vacuum-UV spectra of supersonic jets of ArKrXe mixtures excited by an electron beam

The vacuum-UV spectra of supersonic jets of ArKrXe mixtures excited by an electronic beam were investigated. At small concentrations of Kr and Xe admixtures to the Ar jet, intensive continuous spectra of Kr and Xe were observed. Continuous spectra with intensity maxima at 1350 Å and 1540 Å were also recorded and interpreted as the spectra of the heteroatomic molecules ArKr and KrXe.

Partial structure factors in the long wavelength limit for binary liquid mixtures of argon-krypton and krypton-xenon

Available thermodynamic data have been used to calculate the partial structure factors in the long wavelength limit for binary mixtures of Ar–Kr and of Kr–Xe. Comparison with statistical models for binary mixtures shows that the composition dependence of the partial structure factors is determined primarily by the nonzero interaction between components. The partial structure factors are used to show that spatial correlations of like atoms are preferred over correlations of unlike atoms in both Ar–Kr and Kr–Xe mixtures.

Non-Metastable Penning Effect in the Alpha-Particle Ionization of Inert Gas Mixtures

An experimental investigation has been performed of the ionization yield by α particles in binary gas mixtures over the whole range of mixing ratio. The ionization yield for A-N 2 mixture, in which their ionization potentials are almost equal, agrees numerically well with the estimate from the theory proposed by Huber et al. on the assumption that the ionization yield in the individual component gas is proportional to the energy dissipated primarily by the α-particle in the gas. The additional ionization yield over the estimate from the theory is observed for He-Ne, A-Kr, A-Xe and Kr-Xe mixtures when the second gas is contained more than several percent in the mixture. This can be interpreted by the non-metastable Penning (NMP) ionization. For He-A mixture, the relative contribution of the NMP and metastable Penning (MP) process to the total ionization yield is estimated.

CATAPHORETIC SEGREGATION PROCESSES IN KRYPTON-XENON MIXTURE

Direct evidence of the cataphoretic segregation of small amounts of xenon in krypton is presented. The phenomenon of cataphoresis in Kr–Xe mixtures is explained on the basis of ionic reactions.